1. Field of the Invention
The invention relates to a sandwich board for erecting clamping devices for workpieces. The sandwich board comprises an upper plate forming the clamping surface provided with fastening bores, a lower plate forming a support surface, and support bodies arranged therebetween.
2. Description of the Related Art
Sandwich boards are monocoque construction components which are stiffened or reinforced across their entire surface and in all directions. They fulfill requirements with regard to uniform distribution of stresses, greatest possible shape stability, high and uniform strength against bulging and buckling while having a relatively low weight. The sandwich boards of the aforementioned kind are preferably used in connection with clamping systems for workpieces which serve for clamping and fixation of workpieces on machine tools and measuring devices.
Such a clamping system is known from European patent 0 222 147 B1. The sandwich board is particularly suitable for erecting such clamping systems. It can also provide the base plate for these known clamping systems. However, other fields of use are also conceivable, for example, their use as high performance transport pallets for such workpiece clamping systems.
European patent application 0 797 043 A2 describes a plate comprised of an aluminum alloy which consists of individual extruded profiles connected in a truss-type construction. The individual profiles are connected with one another by friction welding at the contact or joint locations. When performing friction welding, a special welding tool is used. The movement of the tool relative to the parts to be welded generates the required heat for welding or fusing.
It is an object of the present invention to provide a sandwich board of the aforementioned kind which is comprised preferably of aluminum or an aluminum alloy and which can be produced economically with high precision from standard material.
In accordance with the present invention, this is achieved in that the support bodies are formed as pegs or the like which are fastened by friction welding to one of the plates and are connected by gluing to the other plate.
According to the present intention, the known process of friction welding is used in order to connect the pegs, which may be pins, rods, bars, correspondingly configured connecting elements or spacers, by friction welding to one, preferably the upper one, of the plates. The process of friction welding which is used in this connection is carried out without a tool, i.e., at the location where the welding seam is to be generated, one workpiece is moved relative to the other workpiece causing friction and penetration into the material, wherein the material is transformed into a viscous or pasty state so that a permanent welding connection will result.
When a cylindrical peg is used, it is the workpiece which is rotated about its axis for generating the relative movement. With this type of friction welding a substantially smooth surface is produced on the exterior surface of the plate so that the generally required mechanical after machining is not needed. The welding seams are substantially not recognizable on the corresponding surface of the plates. Only minimal distortion at minimal heat penetration occurs. Materials of very different types can be welded to one another. Preferably, the workpiece clamping systems according to the invention, like the systems of the prior art, are made of aluminum and aluminum alloys.
The peg or pin or similarly configured support body can be configured in very different ways.
On the one hand, it is possible to essentially divide the pegs or pins into two parts or pin sections, wherein the two parts are then connected by friction welding to the correlated plate and the ends of the two parts facing one another are glued together. The glued connection is formed by a conical end of one part or pin section engaging a correspondingly shaped conical recess of the other part or pin section.
However, it is also possible to design the sandwich board such that the glued connection is formed by means of a sleeve friction-welded to the plate opposite the plate to which the peg or pin is connected by friction welding. The sleeve and the peg or pin are then glued together. Accordingly, the peg or pin is connected by friction welding to one of the plates and a sleeve is connected by friction welding to the other plate. The peg or pin engages the sleeve and is secured to the sleeve by gluing.
In the context of the present intention, many different support body or pin configurations and many different types of glued connections are conceivable.